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Tuffs SW, Dufresne K, Rishi A, Walton NR, McCormick JK. Novel insights into the immune response to bacterial T cell superantigens. Nat Rev Immunol 2024; 24:417-434. [PMID: 38225276 DOI: 10.1038/s41577-023-00979-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2023] [Indexed: 01/17/2024]
Abstract
Bacterial T cell superantigens (SAgs) are a family of microbial exotoxins that function to activate large numbers of T cells simultaneously. SAgs activate T cells by direct binding and crosslinking of the lateral regions of MHC class II molecules on antigen-presenting cells with T cell receptors (TCRs) on T cells; these interactions alter the normal TCR-peptide-MHC class II architecture to activate T cells in a manner that is independent of the antigen specificity of the TCR. SAgs have well-recognized, central roles in human diseases such as toxic shock syndrome and scarlet fever through their quantitative effects on the T cell response; in addition, numerous other consequences of SAg-driven T cell activation are now being recognized, including direct roles in the pathogenesis of endocarditis, bloodstream infections, skin disease and pharyngitis. In this Review, we summarize the expanding family of bacterial SAgs and how these toxins can engage highly diverse adaptive immune receptors. We highlight recent findings regarding how SAg-driven manipulation of the adaptive immune response may operate in multiple human diseases, as well as contributing to the biology and life cycle of SAg-producing bacterial pathogens.
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Affiliation(s)
- Stephen W Tuffs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Karine Dufresne
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Aanchal Rishi
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Nicholas R Walton
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - John K McCormick
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada.
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Zhu Z, Hu Z, Li S, Fang R, Ono HK, Hu DL. Molecular Characteristics and Pathogenicity of Staphylococcus aureus Exotoxins. Int J Mol Sci 2023; 25:395. [PMID: 38203566 PMCID: PMC10778951 DOI: 10.3390/ijms25010395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/24/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
Staphylococcus aureus stands as one of the most pervasive pathogens given its morbidity and mortality worldwide due to its roles as an infectious agent that causes a wide variety of diseases ranging from moderately severe skin infections to fatal pneumonia and sepsis. S. aureus produces a variety of exotoxins that serve as important virulence factors in S. aureus-related infectious diseases and food poisoning in both humans and animals. For example, staphylococcal enterotoxins (SEs) produced by S. aureus induce staphylococcal foodborne poisoning; toxic shock syndrome toxin-1 (TSST-1), as a typical superantigen, induces toxic shock syndrome; hemolysins induce cell damage in erythrocytes and leukocytes; and exfoliative toxin induces staphylococcal skin scalded syndrome. Recently, Panton-Valentine leucocidin, a cytotoxin produced by community-associated methicillin-resistant S. aureus (CA-MRSA), has been reported, and new types of SEs and staphylococcal enterotoxin-like toxins (SEls) were discovered and reported successively. This review addresses the progress of and novel insights into the molecular structure, biological activities, and pathogenicity of both the classic and the newly identified exotoxins produced by S. aureus.
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Affiliation(s)
- Zhihao Zhu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Zuo Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Shaowen Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Rendong Fang
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China;
| | - Hisaya K. Ono
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Dong-Liang Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
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Hu DL, Li S, Fang R, Ono HK. Update on molecular diversity and multipathogenicity of staphylococcal superantigen toxins. ANIMAL DISEASES 2021. [DOI: 10.1186/s44149-021-00007-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AbstractStaphylococcal superantigen (SAg) toxins are the most notable virulence factors associated with Staphylococcus aureus, which is a pathogen associated with serious community and hospital acquired infections in humans and various diseases in animals. Recently, SAg toxins have become a superfamily with 29 types, including staphylococcal enterotoxins (SEs) with emetic activity, SE-like toxins (SEls) that do not induce emesis in primate models or have yet not been tested, and toxic shock syndrome toxin-1 (TSST-1). SEs and SEls can be subdivided into classical types (SEA to SEE) and novel types (SEG to SElY, SE01, SE02, SEl26 and SEl27). The genes of SAg toxins are located in diverse accessory genetic elements and share certain structural and biological properties. SAg toxins are heat-stable proteins that exhibit pyrogenicity, superantigenicity and capacity to induce lethal hypersensitivity to endotoxin in humans and animals. They have multiple pathogenicities that can interfere with normal immune function of host, increase the chances of survival and transmission of pathogenic bacteria in host, consequently contribute to the occurrence and development of various infections, persistent infections or food poisoning. This review focuses on the following aspects of SAg toxins: (1) superfamily members of classic and novelty discovered staphylococcal SAgs; (2) diversity of gene locations and molecular structural characteristics; (3) biological characteristics and activities; (4) multi-pathogenicity of SAgs in animal and human diseases, including bovine mastitis, swine sepsis, abscesses and skin edema in pig, arthritis and septicemia in poultry, and nosocomial infections and food-borne diseases in humans.
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T Cell Immunity to Bacterial Pathogens: Mechanisms of Immune Control and Bacterial Evasion. Int J Mol Sci 2020; 21:ijms21176144. [PMID: 32858901 PMCID: PMC7504484 DOI: 10.3390/ijms21176144] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
The human body frequently encounters harmful bacterial pathogens and employs immune defense mechanisms designed to counteract such pathogenic assault. In the adaptive immune system, major histocompatibility complex (MHC)-restricted αβ T cells, along with unconventional αβ or γδ T cells, respond to bacterial antigens to orchestrate persisting protective immune responses and generate immunological memory. Research in the past ten years accelerated our knowledge of how T cells recognize bacterial antigens and how many bacterial species have evolved mechanisms to evade host antimicrobial immune responses. Such escape mechanisms act to corrupt the crosstalk between innate and adaptive immunity, potentially tipping the balance of host immune responses toward pathological rather than protective. This review examines the latest developments in our knowledge of how T cell immunity responds to bacterial pathogens and evaluates some of the mechanisms that pathogenic bacteria use to evade such T cell immunosurveillance, to promote virulence and survival in the host.
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Tam K, Torres VJ. Staphylococcus aureus Secreted Toxins and Extracellular Enzymes. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0039-2018. [PMID: 30873936 PMCID: PMC6422052 DOI: 10.1128/microbiolspec.gpp3-0039-2018] [Citation(s) in RCA: 190] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus is a formidable pathogen capable of causing infections in different sites of the body in a variety of vertebrate animals, including humans and livestock. A major contribution to the success of S. aureus as a pathogen is the plethora of virulence factors that manipulate the host's innate and adaptive immune responses. Many of these immune modulating virulence factors are secreted toxins, cofactors for activating host zymogens, and exoenzymes. Secreted toxins such as pore-forming toxins and superantigens are highly inflammatory and can cause leukocyte cell death by cytolysis and clonal deletion, respectively. Coagulases and staphylokinases are cofactors that hijack the host's coagulation system. Exoenzymes, including nucleases and proteases, cleave and inactivate various immune defense and surveillance molecules, such as complement factors, antimicrobial peptides, and surface receptors that are important for leukocyte chemotaxis. Additionally, some of these secreted toxins and exoenzymes can cause disruption of endothelial and epithelial barriers through cell lysis and cleavage of junction proteins. A unique feature when examining the repertoire of S. aureus secreted virulence factors is the apparent functional redundancy exhibited by the majority of the toxins and exoenzymes. However, closer examination of each virulence factor revealed that each has unique properties that have important functional consequences. This chapter provides a brief overview of our current understanding of the major secreted virulence factors critical for S. aureus pathogenesis.
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Affiliation(s)
- Kayan Tam
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
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Immunochemical assay with monoclonal antibodies for detection of staphylococcal enterotoxin H. J Food Drug Anal 2018; 26:741-750. [PMID: 29567245 PMCID: PMC9322225 DOI: 10.1016/j.jfda.2017.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 09/26/2017] [Accepted: 10/27/2017] [Indexed: 01/15/2023] Open
Abstract
Staphylococcal enterotoxins cause food poisoning of various degrees of severity. For milk and meat products, there is a high probability of contamination with staphylococcal enterotoxin H (SEH). In this regard specific and sensitive methods are required to be developed for its detection and monitoring. In this work, the gene seh was expressed and a preparation of recombinant toxin was obtained. Using hybridoma technology, a panel of high-affinity monoclonal antibodies (mAbs) to SEH was produced. The antibodies were characterized and shown to have no cross-reactivity towards the main staphylococcal enterotoxins (A, B, C1, D, E, G and I). Based on these mAbs, a method for specific and quantitative detection of SEH was developed in the format of sandwich enzyme immunoassay (linear range, 0.2–3 ng/ml). All the mAbs produced revealed SEH by immunoblotting. Immunochemical analysis of the culture fluids of staphylococcal isolates obtained from the milk of mastitis-infected cows by immunoblotting and sandwich enzyme immunoassay demonstrated the conformity of these methods. Using the developed method, the toxin was revealed in blood serum and liquid food products practically to 100%. From non-liquid foods, it was shown to be extracted to a maximum with a buffer of pH 4.0–4.5.
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Benkerroum N. Staphylococcal enterotoxins and enterotoxin-like toxins with special reference to dairy products: An overview. Crit Rev Food Sci Nutr 2017; 58:1943-1970. [DOI: 10.1080/10408398.2017.1289149] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Noreddine Benkerroum
- Department of Food Science and Agricultural Chemistry, Macdonald-Stewart Building, McGill University, Macdonald Campus, Sainte-Anne-de-Bellevue, Canada
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Staphylococcus enterotoxin profile of China isolates and the superantigenicity of some novel enterotoxins. Arch Microbiol 2017; 199:723-736. [PMID: 28235987 DOI: 10.1007/s00203-017-1345-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 12/28/2016] [Accepted: 01/20/2017] [Indexed: 10/20/2022]
Abstract
The genus of staphylococcus widely distributes in environments and contributes to a variety of animal and human diseases. The enterotoxins (SEs) secreted by this type of pathogen have been the leading cause of bacterial toxic shock syndrome and food poisoning, and thus present a substantial concern to public health. In this study, we analyzed the superantigen profile of 122 staphylococcus strains isolated from diverse sources. When screened for the presence and prevalence of 17 known se or se-like (sel) genes, except selj, all other genes were detected in these isolates. In particular, 95.9% of the isolates harbored at least one se/sel gene. Moreover, 47.5% of them bore at least 5. Remarkably, several non-pathogenic species of animal- and environment-origin were also found to carry multiple se/sels. The most frequent genes detected were tsst (62.3%), sei (54.1%), and seb (46.7%), followed by some sel genes (selo, selu, and selm), which also were present at relatively high frequency (20-30%). The generated data improved understanding of strain-specific differences in enterotoxin expression. The gene products of the latter (selo and selu) were subsequently analyzed for their antigenicity in a mouse model using purified E. coli-based recombinant proteins. The studies revealed a strong activity for SEO in induction of T-lymphocyte proliferation and production of various inflammatory cytokines either in vivo or in vitro. In contrast, SEU exhibited little superantigenic effects. The molecular basis for the difference in antigenicity was analyzed by 3D homology remodeling, which revealed a difference in binding and affinities for MHC-II molecules and TCR Vβ region.
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Rukkawattanakul T, Sookrung N, Seesuay W, Onlamoon N, Diraphat P, Chaicumpa W, Indrawattana N. Human scFvs That Counteract Bioactivities of Staphylococcus aureus TSST-1. Toxins (Basel) 2017; 9:toxins9020050. [PMID: 28218671 PMCID: PMC5331430 DOI: 10.3390/toxins9020050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 02/09/2017] [Indexed: 11/16/2022] Open
Abstract
Some Staphylococcus aureus isolates produced toxic shock syndrome toxin-1 (TSST-1) which is a pyrogenic toxin superantigen (PTSAg). The toxin activates a large fraction of peripheral blood T lymphocytes causing the cells to proliferate and release massive amounts of pro-inflammatory cytokines leading to a life-threatening multisystem disorder: toxic shock syndrome (TSS). PTSAg-mediated-T cell stimulation circumvents the conventional antigenic peptide presentation to T cell receptor (TCR) by the antigen-presenting cell (APC). Instead, intact PTSAg binds directly to MHC-II molecule outside peptide binding cleft and simultaneously cross-links TCR-Vβ region. Currently, there is neither specific TSS treatment nor drug that directly inactivates TSST-1. In this study, human single chain antibodies (HuscFvs) that bound to and neutralized bioactivities of the TSST-1 were generated using phage display technology. Three E. coli clones transfected with TSST-1-bound phages fished-out from the human scFv library using recombinant TSST-1 as bait expressed TSST-1-bound-HuscFvs that inhibited the TSST-1-mediated T cell activation and pro-inflammatory cytokine gene expressions and productions.Computerized simulation, verified by mutations of the residues of HuscFv complementarity determining regions (CDRs),predicted to involve in target binding indicated that the HuscFvs formed interface contact with the toxin residues important for immunopathogenesis. The HuscFvs have high potential for future therapeutic application.
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MESH Headings
- Antibodies, Monoclonal, Humanized/genetics
- Antibodies, Monoclonal, Humanized/metabolism
- Antibodies, Monoclonal, Humanized/pharmacology
- Antibodies, Neutralizing/genetics
- Antibodies, Neutralizing/metabolism
- Antibodies, Neutralizing/pharmacology
- Bacterial Toxins/antagonists & inhibitors
- Bacterial Toxins/genetics
- Bacterial Toxins/immunology
- Bacterial Toxins/metabolism
- Cell Surface Display Techniques
- Cells, Cultured
- Cytokines/metabolism
- Enterotoxins/antagonists & inhibitors
- Enterotoxins/genetics
- Enterotoxins/immunology
- Enterotoxins/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Histocompatibility Antigens Class II/metabolism
- Host-Pathogen Interactions
- Humans
- Inflammation Mediators/metabolism
- Lymphocyte Activation/drug effects
- Mutation
- Protein Binding
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Shock, Septic/immunology
- Shock, Septic/metabolism
- Shock, Septic/microbiology
- Shock, Septic/prevention & control
- Single-Chain Antibodies/genetics
- Single-Chain Antibodies/metabolism
- Single-Chain Antibodies/pharmacology
- Staphylococcal Infections/immunology
- Staphylococcal Infections/metabolism
- Staphylococcal Infections/microbiology
- Staphylococcal Infections/prevention & control
- Staphylococcus aureus/drug effects
- Staphylococcus aureus/genetics
- Staphylococcus aureus/immunology
- Staphylococcus aureus/metabolism
- Superantigens/genetics
- Superantigens/immunology
- Superantigens/metabolism
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- T-Lymphocytes/microbiology
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Affiliation(s)
- Thunchanok Rukkawattanakul
- Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Nitat Sookrung
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Watee Seesuay
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Nattawat Onlamoon
- Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Pornphan Diraphat
- Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand.
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Nitaya Indrawattana
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
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Rödström KEJ, Regenthal P, Lindkvist-Petersson K. Structure of Staphylococcal Enterotoxin E in Complex with TCR Defines the Role of TCR Loop Positioning in Superantigen Recognition. PLoS One 2015; 10:e0131988. [PMID: 26147596 PMCID: PMC4492778 DOI: 10.1371/journal.pone.0131988] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/09/2015] [Indexed: 11/18/2022] Open
Abstract
T cells are crucial players in cell-mediated immunity. The specificity of their receptor, the T cell receptor (TCR), is central for the immune system to distinguish foreign from host antigens. Superantigens are bacterial toxins capable of inducing a toxic immune response by cross-linking the TCR and the major histocompatibility complex (MHC) class II and circumventing the antigen specificity. Here, we present the structure of staphylococcal enterotoxin E (SEE) in complex with a human T cell receptor, as well as the unligated T cell receptor structure. There are clear structural changes in the TCR loops upon superantigen binding. In particular, the HV4 loop moves to circumvent steric clashes upon complex formation. In addition, a predicted ternary model of SEE in complex with both TCR and MHC class II displays intermolecular contacts between the TCR α-chain and the MHC, suggesting that the TCR α-chain is of importance for complex formation.
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Affiliation(s)
- Karin E. J. Rödström
- Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden
| | - Paulina Regenthal
- Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden
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Kang H, Deng H, Shen M, He X, Xia Y, Li Y, Liang Z, Wang H, Huang J. Superantigenicity analysis of staphylococcal enterotoxins SElK and SElQ in a mouse model. RSC Adv 2015. [DOI: 10.1039/c4ra16649c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Staphylococcal enterotoxins (SEs) are superantigenic toxins secreted byStaphylococcus aureusthat is involved in causing food poisoning and human diseases.
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Affiliation(s)
- Hongzhi Kang
- School of Chemical Engineering and Technology
- Tianjin University
- Tianjin
- China
| | - Hui Deng
- School of Life Sciences
- Tianjin University
- Tianjin
- China
| | - Menglu Shen
- School of Life Sciences
- Tianjin University
- Tianjin
- China
| | - Xianzhi He
- School of Life Sciences
- Tianjin University
- Tianjin
- China
| | - Yihe Xia
- School of Life Sciences
- Tianjin University
- Tianjin
- China
| | - Yi Li
- School of Life Sciences
- Tianjin University
- Tianjin
- China
| | - Zhixuan Liang
- Tianjin Center of Animal Disease Preventive and Control
- Tianjin
- China
| | - Hongjun Wang
- Tianjin Center of Animal Disease Preventive and Control
- Tianjin
- China
| | - Jinhai Huang
- School of Chemical Engineering and Technology
- Tianjin University
- Tianjin
- China
- School of Life Sciences
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12
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Li L, Qiu Z, Li Y, Liang F, Ye H, Cai Y, Guo W, Li Y, Yue J. Herpes B virus gD interaction with its human receptor--an in silico analysis approach. Theor Biol Med Model 2014; 11:27. [PMID: 24902525 PMCID: PMC4106229 DOI: 10.1186/1742-4682-11-27] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 05/22/2014] [Indexed: 12/17/2022] Open
Abstract
Background The glycoprotein D (gD) is essential for Herpes B virus (BV) entry into mammalian cells. Nectin-1, an HSV-1 gD receptor, is found to be the receptor which mediated BV induced cell-cell fusion, while HVEM does not mediate fusion by BV glycoprotein. However, the specific sequence and structural requirements of the BV gD for the recognition of and binding to Nectin-1 are unknown. Moreover, the 3D structures of BV gD and the BV gD-receptor complex have not been determined. In this study, we propose a reliable model of the interaction of the BV gD with receptor using bioinformatics tools. Results The three-dimensional structures of two BV gD-receptor complexes were constructed using homology modelling and docking strategy. Based on the models of these complexes, the BV gD receptor interaction patterns were calculated. The results showed that the interface between the BV gD and nectin-1 molecule is not geometrically complementary. The computed molecular interactions indicated that two terminal extensions were the main region of BV gD that binds to nectin-1 and that hydrophobic contacts between the two molecules play key roles in their recognition and binding. The constructed BV gD-HVEM complex model showed that this complex had a lower shape complementarity value and a smaller interface area compared with the HSV-1 gD-HVEM complex, and the number of intermolecular interactions between BV gD-HVEM were fewer than that of HSV-1 gD-HVEM complex. These results could explain why HVEM does not function as a receptor for BV gD. Conclusion In this study, we present structural model for the BV gD in a complex with its receptor. Some features predicted by this model can explain previously reported experimental data. This complex model may lead to a better understanding of the function of BV gD and its interaction with receptor and will improve our understanding of the activation of the BV fusion and entry process.
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Affiliation(s)
| | | | | | | | | | | | - Wanfeng Guo
- Hospital No,307 of PLA, the Academy of Military Medical Sciences, Beijing 100071, China.
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13
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Kasper KJ, Zeppa JJ, Wakabayashi AT, Xu SX, Mazzuca DM, Welch I, Baroja ML, Kotb M, Cairns E, Cleary PP, Haeryfar SMM, McCormick JK. Bacterial superantigens promote acute nasopharyngeal infection by Streptococcus pyogenes in a human MHC Class II-dependent manner. PLoS Pathog 2014; 10:e1004155. [PMID: 24875883 PMCID: PMC4038607 DOI: 10.1371/journal.ppat.1004155] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/17/2014] [Indexed: 11/19/2022] Open
Abstract
Establishing the genetic determinants of niche adaptation by microbial pathogens to specific hosts is important for the management and control of infectious disease. Streptococcus pyogenes is a globally prominent human-specific bacterial pathogen that secretes superantigens (SAgs) as 'trademark' virulence factors. SAgs function to force the activation of T lymphocytes through direct binding to lateral surfaces of T cell receptors and class II major histocompatibility complex (MHC-II) molecules. S. pyogenes invariably encodes multiple SAgs, often within putative mobile genetic elements, and although SAgs are documented virulence factors for diseases such as scarlet fever and the streptococcal toxic shock syndrome (STSS), how these exotoxins contribute to the fitness and evolution of S. pyogenes is unknown. Here we show that acute infection in the nasopharynx is dependent upon both bacterial SAgs and host MHC-II molecules. S. pyogenes was rapidly cleared from the nasal cavity of wild-type C57BL/6 (B6) mice, whereas infection was enhanced up to ∼10,000-fold in B6 mice that express human MHC-II. This phenotype required the SpeA superantigen, and vaccination with an MHC -II binding mutant toxoid of SpeA dramatically inhibited infection. Our findings indicate that streptococcal SAgs are critical for the establishment of nasopharyngeal infection, thus providing an explanation as to why S. pyogenes produces these potent toxins. This work also highlights that SAg redundancy exists to avoid host anti-SAg humoral immune responses and to potentially overcome host MHC-II polymorphisms.
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Affiliation(s)
- Katherine J. Kasper
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Joseph J. Zeppa
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Adrienne T. Wakabayashi
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Stacey X. Xu
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Delfina M. Mazzuca
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Ian Welch
- Department of Animal Care and Veterinary Services, Western University, London, Ontario, Canada
| | - Miren L. Baroja
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - Malak Kotb
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Ewa Cairns
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - P. Patrick Cleary
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - S. M. Mansour Haeryfar
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - John K. McCormick
- Department of Microbiology and Immunology and the Centre for Human Immunology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- * E-mail:
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14
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Detection and measurement of staphylococcal enterotoxin-like K (SEl-K) secretion by Staphylococcus aureus clinical isolates. J Clin Microbiol 2014; 52:2536-43. [PMID: 24808237 DOI: 10.1128/jcm.00387-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Staphylococcal enterotoxin-like K (SEl-K) is a potent mitogen that elicits T-cell proliferation and cytokine production at very low concentrations. However, unlike the classical enterotoxins SEB and toxic shock syndrome toxin 1 (TSST-1), the gene for SEl-K is commonly present in more than half of all Staphylococcus aureus clinical isolates and is present in almost all USA300 community-acquired methicillin-resistant S. aureus (CA-MRSA) isolates. Sequencing of the sel-k gene in over 20 clinical isolates and comparative analysis with all 14 published sel-k sequences indicate that there are at least 6 variants of the sel-k gene, including one that is conserved among all examined USA300 strains. Additionally, we have developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) that specifically detects and measures SEl-K protein in culture supernatants and biological fluids. Quantification of in vitro SEl-K secretion by various S. aureus isolates using this novel capture ELISA revealed detectable amounts of SEl-K secretion by all isolates, with the highest secretion levels being exhibited by MRSA strains that coexpress SEB. In vivo secretion was measured in a murine thigh abscess model, where similar levels of SEl-K accumulation were noted regardless of whether the infecting strain exhibited high or low secretion of SEl-K in vitro. We conclude that SEl-K is commonly expressed in the setting of staphylococcal infection, in significant amounts. SEl-K should be further explored as a target for passive immunotherapy against complicated S. aureus infection.
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Abstract
SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.
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16
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Gu L, Yue J, Zheng Y, Zheng X, Wang J, Wang Y, Li J, Jiang Y, Jiang H. Evaluation of a recombinant double mutant of staphylococcal enterotoxin B (SEB-H32Q/K173E) with enhanced antitumor activity effects and decreased pyrexia. PLoS One 2013; 8:e55892. [PMID: 23405232 PMCID: PMC3566101 DOI: 10.1371/journal.pone.0055892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 01/07/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Immunotherapy has been used to improve patient immune function, inhibit tumor growth and has become a highly promising method of cancer treatment. Highly agglutinative staphylococcin (HAS), a mixture of Staphylococcus aureus culture filtrates, which include staphylococcal enterotoxin (SE) C as the active ingredient, has been used clinically as an immunomodifier in the treatment of a number of tumors for many years. However, the use of HAS has been associated with some unavoidable side-effects such as fever. Previous studies have shown that SEB stimulates a more potent activation of T lymphocytes than SEC3, and mutations of the histidine residues eliminated the toxicity of SEB. SE mutants with decreased side-effects and/or more potent antitumor activities are required. METHODOLOGY/PRINCIPAL FINDINGS We built a structural model of the MHC II-SEB-TCR complex and found that a mutation of SEB at Lys173 might decrease the repulsion force between the SEB-TCR, which would facilitate their interaction. From the above results, we designed SEB-H32Q/K173E (mSEB). Analysis of in vitro stimulation of the proliferation of human peripheral blood mononuclear cells (PBMCs), IFN-γ secretion and inhibition of the growth of various tumor cell lines demonstrated that mSEB exhibited higher antitumor activity compared with wild-type SEB (wtSEB). Notably, mSEB inhibited the growth of various tumors at an extremely low concentration with little cytotoxicity against normal cells. Three animal tumor models (C57BL/6 mouse, New Zealand rabbit and a humanized NOD/SCID mouse) were used to evaluate the in vivo immunotherapeutic effects. Compared with wtSEB, mSEB significantly enhanced antitumor effect in more than one animal model with reduced pyrexia toxicity and prolonged the survival of tumor-bearing mice. CONCLUSIONS/SIGNIFICANCE Our results suggest that SEB-H32Q/K173E retains superantigen (SAg) characteristics and enhances the host immune response to neoplastic diseases while reducing associated pyrogenic toxicity.
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MESH Headings
- Animals
- Carcinoma, Lewis Lung/genetics
- Carcinoma, Lewis Lung/immunology
- Carcinoma, Lewis Lung/therapy
- Cytokines/metabolism
- Cytotoxicity, Immunologic
- Enterotoxins/genetics
- Enterotoxins/immunology
- Enterotoxins/metabolism
- Female
- Fever/genetics
- Fever/immunology
- Fever/therapy
- Genes, MHC Class II/genetics
- Genes, MHC Class II/immunology
- Humans
- Immunotherapy
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Lymphocyte Activation/immunology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, SCID
- Mutant Proteins/therapeutic use
- Mutation/genetics
- Rabbits
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/immunology
- Recombinant Proteins/therapeutic use
- Staphylococcus aureus/metabolism
- Survival Rate
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Affiliation(s)
- Liwei Gu
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
- Department of Traditional Chinese Medicine Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
| | - Junjie Yue
- Beijing Institute of Biotechnology, Beijing, China
| | - Yuling Zheng
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
| | - Xin Zheng
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
| | - Jun Wang
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
| | - Yanzi Wang
- Department of Pharmacy, Jiangsu Provincial Xuzhou Pharmaceutical Vocational College, Xuzhou, China
| | - Jianchun Li
- Department of Traditional Chinese Medicine Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
- * E-mail: (JCL); (YQJ); (HJ)
| | - Yongqiang Jiang
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
- * E-mail: (JCL); (YQJ); (HJ)
| | - Hua Jiang
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, China
- * E-mail: (JCL); (YQJ); (HJ)
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17
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Maina EK, Hu DL, Asano K, Nakane A. Inhibition of emetic and superantigenic activities of staphylococcal enterotoxin A by synthetic peptides. Peptides 2012; 38:1-7. [PMID: 22955031 DOI: 10.1016/j.peptides.2012.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 08/17/2012] [Accepted: 08/17/2012] [Indexed: 11/25/2022]
Abstract
Staphylococcus aureus is a major human pathogen producing different types of toxins. Enterotoxin A (SEA) is the most common type among clinical and food-related strains. The aim of the present study was to estimate functional regions of SEA that are responsible for emetic and superantigenic activities using synthetic peptides. A series of 13 synthetic peptides corresponding to specific regions of SEA were synthesized, and the effect of these peptides on superantigenic activity of SEA including interferon γ (IFN-γ) production in mouse spleen cells, SEA-induced lethal shock in mice, spleen cell proliferation in house musk shrew, and emetic activity in shrews were assessed. Pre-treatment of spleen cells with synthetic peptides corresponding to the regions 21-40, 35-50, 81-100, or 161-180 of SEA significantly inhibited SEA-induced IFN-γ production and cell proliferation. These peptides also inhibited SEA-induced lethal shock. Interestingly, peptides corresponding to regions 21-40, 35-50 and 81-100 significantly inhibited SEA-induced emesis in house musk shrews, but region 161-180 did not. These findings indicated that regions 21-50 and 81-100 of SEA are important for both superantigenic and emetic activities of SEA molecule while region 161-180 is involved in superantigenic activity but not emetic activity of SEA. These regions could be important targets for therapeutic intervention against SEA exposure.
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Affiliation(s)
- Edward K Maina
- Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
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18
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Xu SX, McCormick JK. Staphylococcal superantigens in colonization and disease. Front Cell Infect Microbiol 2012; 2:52. [PMID: 22919643 PMCID: PMC3417409 DOI: 10.3389/fcimb.2012.00052] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/29/2012] [Indexed: 12/28/2022] Open
Abstract
Superantigens (SAgs) are a family of potent immunostimulatory exotoxins known to be produced by only a few bacterial pathogens, including Staphylococcus aureus. More than 20 distinct SAgs have been characterized from different S. aureus strains and at least 80% of clinical strains harbor at least one SAg gene, although most strains encode many. SAgs have been classically associated with food poisoning and toxic shock syndrome (TSS), for which these toxins are the causative agent. TSS is a potentially fatal disease whereby SAg-mediated activation of T cells results in overproduction of cytokines and results in systemic inflammation and shock. Numerous studies have also shown a possible role for SAgs in other diseases such as Kawasaki disease (KD), atopic dermatitis (AD), and chronic rhinosinusitis (CRS). There is also now a rich understanding of the mechanisms of action of SAgs, as well as their structures and function. However, we have yet to discover what purpose SAgs play in the life cycle of S. aureus, and why such a wide array of these toxins exists. This review will focus on recent developments within the SAg field in terms of the molecular biology of these toxins and their role in both colonization and disease.
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Affiliation(s)
- Stacey X Xu
- Department of Microbiology and Immunology, Centre for Human Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London ON, Canada
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19
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Staphylococcal enterotoxin A has potent superantigenic and emetic activities but not diarrheagenic activity. Int J Med Microbiol 2012; 302:88-95. [PMID: 22424598 DOI: 10.1016/j.ijmm.2012.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/10/2012] [Accepted: 01/15/2012] [Indexed: 11/21/2022] Open
Abstract
Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus are pyrogenic superantigenic toxins that are involved in human diseases including food poisoning and toxic shock syndrome. Although the superantigenic activity of SEs has been well characterized, its role and mechanism in clinical symptoms of food poisoning remain poorly understood. In this study, house musk shrews (Suncus murinus), a small emetic animal model, were used to study the role of SEs in clinical manifestations of food poisoning. Administration of SEA induced a potent emetic response in vivo and showed significant superantigenic activity in vitro in house musk shrews. However, SEA revealed no diarrheagenic activity. SEA directly injected into the intestinal loops of house musk shrews failed to induce fluid exudation and consequent dilation of the intestinal segments. Rabbit intestinal loop experiments were further carried out to confirm the results and also showed that SEA induced no fluid exudation and consequent dilation. Furthermore, the SEA-producing S. aureus also failed to induce fluid exudation in the administered loops of these animal models. These results indicate that SEA has potent superantigenic and emetic activities, but does not have a diarrheagenic activity.
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20
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Hennekinne JA, De Buyser ML, Dragacci S. Staphylococcus aureus and its food poisoning toxins: characterization and outbreak investigation. FEMS Microbiol Rev 2011; 36:815-36. [PMID: 22091892 DOI: 10.1111/j.1574-6976.2011.00311.x] [Citation(s) in RCA: 536] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 09/15/2011] [Accepted: 10/03/2011] [Indexed: 11/29/2022] Open
Abstract
Staphylococcal food poisoning (SFP) is one of the most common food-borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All of them have superantigenic activity whereas half of them have been proved to be emetic, representing a potential hazard for consumers. This review, divided into four parts, will focus on the following: (1) the worldwide story of SFP outbreaks, (2) the characteristics and behaviour of S. aureus in food environment, (3) the toxinogenic conditions and characteristics of SEs, and (4) SFP outbreaks including symptomatology, occurrence in the European Union and currently available methods used to characterize staphylococcal outbreaks.
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Affiliation(s)
- Jacques-Antoine Hennekinne
- French Agency for Food, Environmental and Occupational Health & Safety (Anses), Food Safety Laboratory of Maisons-Alfort, European Union Reference Laboratory for Coagulase Positive Staphylococci, Maisons-Alfort, France.
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21
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van der Fits L, Sandberg Y, Darzentas N, Zoutman W, Tielemans D, Wolvers-Tettero I, Vermeer M, Langerak A. A restricted clonal T-cell receptor αβ repertoire in Sézary syndrome is indicative of superantigenic stimulation. Br J Dermatol 2011; 165:78-84. [DOI: 10.1111/j.1365-2133.2011.10308.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Brosnahan AJ, Schlievert PM. Gram-positive bacterial superantigen outside-in signaling causes toxic shock syndrome. FEBS J 2011; 278:4649-67. [PMID: 21535475 DOI: 10.1111/j.1742-4658.2011.08151.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcus aureus and Streptococcus pyogenes (group A streptococci) are Gram-positive pathogens capable of producing a variety of bacterial exotoxins known as superantigens. Superantigens interact with antigen-presenting cells (APCs) and T cells to induce T cell proliferation and massive cytokine production, which leads to fever, rash, capillary leak and subsequent hypotension, the major symptoms of toxic shock syndrome. Both S. aureus and group A streptococci colonize mucosal surfaces, including the anterior nares and vagina for S. aureus, and the oropharynx and less commonly the vagina for group A streptococci. However, due to their abilities to secrete a variety of virulence factors, the organisms can also cause illnesses from the mucosa. This review provides an updated discussion of the biochemical and structural features of one group of secreted virulence factors, the staphylococcal and group A streptococcal superantigens, and their abilities to cause toxic shock syndrome from a mucosal surface. The main focus of this review, however, is the abilities of superantigens to induce cytokines and chemokines from epithelial cells, which has been linked to a dodecapeptide region that is relatively conserved among all superantigens and is distinct from the binding sites required for interactions with APCs and T cells. This phenomenon, termed outside-in signaling, acts to recruit adaptive immune cells to the submucosa, where the superantigens can then interact with those cells to initiate the final cytokine cascades that lead to toxic shock syndrome.
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Affiliation(s)
- Amanda J Brosnahan
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, USA
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23
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Nur-ur Rahman AKM, Bonsor DA, Herfst CA, Pollard F, Peirce M, Wyatt AW, Kasper KJ, Madrenas J, Sundberg EJ, McCormick JK. The T cell receptor beta-chain second complementarity determining region loop (CDR2beta governs T cell activation and Vbeta specificity by bacterial superantigens. J Biol Chem 2010; 286:4871-81. [PMID: 21127057 DOI: 10.1074/jbc.m110.189068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Superantigens (SAgs) are microbial toxins defined by their ability to activate T lymphocytes in a T cell receptor (TCR) β-chain variable domain (Vβ)-specific manner. Although existing structural information indicates that diverse bacterial SAgs all uniformly engage the Vβ second complementarity determining region (CDR2β) loop, the molecular rules that dictate SAg-mediated T cell activation and Vβ specificity are not fully understood. Herein we report the crystal structure of human Vβ2.1 (hVβ2.1) in complex with the toxic shock syndrome toxin-1 (TSST-1) SAg, and mutagenesis of hVβ2.1 indicates that the non-canonical length of CDR2β is a critical determinant for recognition by TSST-1 as well as the distantly related SAg streptococcal pyrogenic exotoxin C. Frame work (FR) region 3 is uniquely critical for TSST-1 function explaining the fine Vβ-specificity exhibited by this SAg. Furthermore, domain swapping experiments with SAgs, which use distinct domains to engage both CDR2β and FR3/4β revealed that the CDR2β contacts dictate T lymphocyte Vβ-specificity. These findings demonstrate that the TCR CDR2β loop is the critical determinant for functional recognition and Vβ-specificity by diverse bacterial SAgs.
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Affiliation(s)
- A K M Nur-ur Rahman
- Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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24
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The structure of superantigen complexed with TCR and MHC reveals novel insights into superantigenic T cell activation. Nat Commun 2010; 1:119. [PMID: 21081917 DOI: 10.1038/ncomms1117] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 10/18/2010] [Indexed: 11/09/2022] Open
Abstract
Superantigens (SAgs) are bacterial toxins that interact with immunoreceptors, T cell receptor (TCR) and major histocompatibility complex (MHC) class II, conventionally through the variable β-domain of TCR (TCRVβ). They induce a massive release of cytokines, which can lead to diseases such as food poisoning and toxic shock syndrome. In this study, we report the X-ray structure of the ternary complex between staphylococcal enterotoxin H (SEH) and its human receptors, MHC class II and TCR. The structure demonstrates that SEH predominantly interacts with the variable α-domain of TCR (TCRVα), which is supported by nuclear magnetic resonance (NMR) analyses. Furthermore, there is no contact between MHC and TCR upon complex formation. Structural analyses suggest that the major contact points to TCRVα are conserved among other bacterial SAgs. Consequently, a new dimension of SAg biology emerges, suggesting that in addition to the conventional interactions with the TCRVβ domain, SAgs can also activate T cells through the TCRVα domain.
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25
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The systemic and pulmonary immune response to staphylococcal enterotoxins. Toxins (Basel) 2010; 2:1898-912. [PMID: 22069664 PMCID: PMC3153275 DOI: 10.3390/toxins2071898] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 07/12/2010] [Indexed: 11/21/2022] Open
Abstract
In response to environmental cues the human pathogen Staphylococcus aureus synthesizes and releases proteinaceous enterotoxins. These enterotoxins are natural etiologic entities of severe food poisoning, toxic shock syndrome, and acute diseases. Staphylococcal enterotoxins are currently listed as Category B Bioterrorism Agents by the Center for Disease Control and Prevention. They are associated with respiratory illnesses, and may contribute to exacerbation of pulmonary disease. This likely stems from the ability of Staphylococcal enterotoxins to elicit powerful episodes of T cell stimulation resulting in release of pro-inflammatory cytokines. Here, we discuss the role of the immune system and potential mechanisms of disease initiation and progression.
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26
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Argudín MÁ, Mendoza MC, Rodicio MR. Food poisoning and Staphylococcus aureus enterotoxins. Toxins (Basel) 2010; 2:1751-73. [PMID: 22069659 PMCID: PMC3153270 DOI: 10.3390/toxins2071751] [Citation(s) in RCA: 609] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/24/2010] [Accepted: 06/30/2010] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and SElQ) or have yet to be tested (SElJ, SElK, SElM to SElP, SElU, SElU2 and SElV). SEs and SEls have been traditionally subdivided into classical (SEA to SEE) and new (SEG to SElU2) types. All possess superantigenic activity and are encoded by accessory genetic elements, including plasmids, prophages, pathogenicity islands, vSa genomic islands, or by genes located next to the staphylococcal cassette chromosome (SCC) implicated in methicillin resistance. SEs are a major cause of food poisoning, which typically occurs after ingestion of different foods, particularly processed meat and dairy products, contaminated with S. aureus by improper handling and subsequent storage at elevated temperatures. Symptoms are of rapid onset and include nausea and violent vomiting, with or without diarrhea. The illness is usually self-limiting and only occasionally it is severe enough to warrant hospitalization. SEA is the most common cause of staphylococcal food poisoning worldwide, but the involvement of other classical SEs has been also demonstrated. Of the new SE/SEls, only SEH have clearly been associated with food poisoning. However, genes encoding novel SEs as well as SEls with untested emetic activity are widely represented in S. aureus, and their role in pathogenesis may be underestimated.
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Affiliation(s)
- María Ángeles Argudín
- Department of Functional Biology (Section of Microbiology) and University Institute of Biotechnology of Asturias (IUBA), University of Oviedo, Oviedo, Spain.
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27
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Abstract
Bacterial toxins damage the host at the site of bacterial infection or distant from the site. Bacterial toxins can be single proteins or oligomeric protein complexes that are organized with distinct AB structure-function properties. The A domain encodes a catalytic activity. ADP ribosylation of host proteins is the earliest post-translational modification determined to be performed by bacterial toxins; other modifications include glucosylation and proteolysis. Bacterial toxins also catalyze the non-covalent modification of host protein function or can modify host cell properties through direct protein-protein interactions. The B domain includes two functional domains: a receptor-binding domain, which defines the tropism of a toxin for a cell and a translocation domain that delivers the A domain across a lipid bilayer, either on the plasma membrane or the endosome. Bacterial toxins are often characterized based upon the secretion mechanism that delivers the toxin out of the bacterium, termed types I-VII. This review summarizes the major families of bacterial toxins and also describes the specific structure-function properties of the botulinum neurotoxins.
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Affiliation(s)
- James S Henkel
- Medical College of Wisconsin, Department of Microbiology and Molecular Genetics, Milwaukee, WI 53151, USA.
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28
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Abstract
T-cell receptors (TCRs) are structurally related to antibodies, and also interact with a diverse set of ligands. TCRs recognize foreign peptide antigens displayed by major histocompatibility complex (MHC) molecules and foreign lipid-based antigens presented by CD1. These interactions initiate an immune response through T-cell activation. These critical surveillance and response initiation functions of the adaptive immune system are not perfect, though, as TCR interactions with self antigens can lead to autoimmune disease. Mutated peptides can also be recognized specifically by TCRs, and may be important in tumor immunity. TCRs are also bound specifically by a family of bacterial toxins called superantigens, which over-stimulate the immune system to cause numerous human diseases.
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Affiliation(s)
- Eric J Sundberg
- Boston Biomedical Research Institute, 64 Grove Street, Watertown, MA 02472, USA
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29
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Rich RL, Myszka DG. Survey of the year 2007 commercial optical biosensor literature. J Mol Recognit 2008; 21:355-400. [DOI: 10.1002/jmr.928] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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30
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Kasper KJ, Xi W, Rahman AKMNU, Nooh MM, Kotb M, Sundberg EJ, Madrenas J, McCormick JK. Molecular requirements for MHC class II alpha-chain engagement and allelic discrimination by the bacterial superantigen streptococcal pyrogenic exotoxin C. THE JOURNAL OF IMMUNOLOGY 2008; 181:3384-92. [PMID: 18714010 DOI: 10.4049/jimmunol.181.5.3384] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Superantigens (SAgs) are microbial toxins that bind to both TCR beta-chain variable domains (Vbetas) and MHC class II molecules, resulting in the activation of T cells in a Vbeta-specific manner. It is now well established that different isoforms of MHC II molecules can play a significant role in the immune response to bacterial SAgs. In this work, using directed mutational studies in conjunction with functional analyses, we provide a complete functional map of the low-affinity MHC II alpha-chain binding interface of the SAg streptococcal pyrogenic exotoxin C (SpeC) and identify a functional epitope in the beta-barrel domain that is required for the activation of T cells. Using cell lines that exclusively express individual MHC II isoforms, our studies provide a molecular basis for the selectivity of SpeC-MHC II recognition, and provide one mechanism by how SAgs are capable of distinguishing between different MHC II alleles.
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Affiliation(s)
- Katherine J Kasper
- Department of Microbiology and Immunology, University of Western Ontario, Canada
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31
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Sundberg EJ, Deng L, Mariuzza RA. TCR recognition of peptide/MHC class II complexes and superantigens. Semin Immunol 2007; 19:262-71. [PMID: 17560120 PMCID: PMC2949352 DOI: 10.1016/j.smim.2007.04.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 04/23/2007] [Accepted: 04/23/2007] [Indexed: 11/21/2022]
Abstract
Major histocompatibility complex (MHC) class II molecules display peptides to the T cell receptor (TCR). The ability of the TCR to discriminate foreign from self-peptides presented by MHC molecules is a requirement of an effective adaptive immune response. Dysregulation of this molecular recognition event often leads to a disease state. Recently, a number of structural studies have provided significant insight into several such dysregulated interactions between peptide/MHC complexes and TCR molecules. These include TCR recognition of self-peptides, which results in autoimmune reactions, and of mutant self-peptides, common in the immunosurveillance of tumors, as well as the engagement of TCRs by superantigens, a family of bacterial toxins responsible for toxic shock syndrome.
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Affiliation(s)
- Eric J Sundberg
- Boston Biomedical Research Institute, Watertown, MA 02472, USA.
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